Classifications

• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B17/00—Mechanisms for stabilising frequency
  • G04B17/20—Compensation of mechanisms for stabilising frequency
  • G04B17/22—Compensation of mechanisms for stabilising frequency for the effect of variations of temperature
  • G04B17/227—Compensation of mechanisms for stabilising frequency for the effect of variations of temperature composition and manufacture of the material used
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B17/00—Mechanisms for stabilising frequency
  • G04B17/20—Compensation of mechanisms for stabilising frequency
  • G04B17/22—Compensation of mechanisms for stabilising frequency for the effect of variations of temperature
  • G04B17/222—Compensation of mechanisms for stabilising frequency for the effect of variations of temperature with balances

Definitions

• the invention relates to a balance for a timepiece comprising a serge, a hub and at least one arm connecting the hub to said serge, at least a portion of the balance being made of a partially or totally amorphous metal alloy.
• the present invention also relates to a method of manufacturing such a balance and a resonator comprising such a balance.
• Such a pendent amorphous metal alloy is described for example in the published application EP 2 466 396.
• the balance is associated with a steel hairspring and is used for the pendulum an amorphous metal alloy based on iron, for its ferromagnetic properties.
• the problem that the invention object of the application EP 2 466 396 seeks to solve therefore concerns the protection of the hairspring against external disturbing magnetic fields which are likely to affect the frequency stability of the resonator.
• the present invention relates to another parameter that may affect the frequency stability of the resonator, and not addressed in EP 2 466 396, namely the thermal variations.
• thermal variations vary the stiffness of the hairspring, as well as the geometries of the hairspring and the balance, which modifies the spring constant and the inertia, and therefore the frequency of oscillation.
• Watchmakers have worked hard to have temperature-stable oscillators and many tracks have been explored / exploited, including one that earned Charles-Edouard Council a Nobel Prize for the development of the Elinvar alloy whose modulus of elasticity increases with temperature and offsets the increase in inertia of the pendulum.
• the monocrystalline quartz spiral allows a thermal compensation of the change of inertia of the balance.
• the quartz is limited to materials having a coefficient of thermal expansion of the order of 10 ppm / ° C, which corresponds for example titanium and platinum.
• the main problem of these materials is the machinability and control of fine structure and / or a perfect finish (mirror polish for example).
• titanium its relatively low density limits its use for large pendulums and in the case of platinum its high price limits its use to prestige and luxury products.
• the object of the present invention is to overcome these drawbacks by proposing a rocker made of new materials making it possible to couple said balance to a hairspring, preferably of monocrystalline quartz, but also of silicon.
• Another object of the present invention is to provide a rocker made of new materials allowing a simpler and more precise manufacture, so as to reduce for example the dispersion of inertia and / or unbalance within the same batch of production.
• the invention relates firstly to a balance for a timepiece comprising a serge, a hub and at least one arm connecting the hub to said serge, at least a portion of the balance being made of an alloy at least partially amorphous metal.
• said at least partially amorphous metal alloy is based on a member selected from the group consisting of platinum, zirconium and titanium, and has a coefficient of thermal expansion of between 7 ppm / ° C and 12 ppm / ° C.
• the present invention also relates to a method of manufacturing a balance wheel for which the serge, the hub and the arms are made of said at least partially amorphous metal alloy based on a member selected from the group consisting of platinum, zirconium and titanium as defined above, comprising the following steps:
• step d) release the balance obtained in step c) of its mold.
• the present invention also relates to a resonator comprising a balance as defined above and a monocrystalline quartz spiral.
• Such an at least partially amorphous metal alloy based on platinum, titanium or zirconium makes it possible to produce a balance that can be paired with a monocrystalline quartz spiral.
• an at least partially amorphous metal alloy balance made of platinum, zirconium or titanium can be realized using a simplified manufacturing process. such as a casting process or a hot forming method.
• the at least partially amorphous metal alloy based on platinum, zirconium or titanium has the property of having a much larger elastic range than its crystalline equivalent, thanks to the absence of dislocation. This property makes it possible to overmould or integrate the balance wheel elements to improve the centering and to adjust the inertia and / or unbalance.
• FIG. 1 is a perspective view of a beam according to the invention.
• FIG. 2 is a partial top view of an alternative embodiment of a beam according to the invention.
• FIG. 3 is a partial top view of another embodiment of a pendulum according to the invention.
• FIG. 4 is a sectional view along the axis A-A of Figure 3.
• FIG. 5 to 10 are partial top views of other embodiments of a beam according to the invention.
• a pendulum 1 for a timepiece Such a rocker 1 comprises in a traditional way a serge 2, continuous or not, defining the outer diameter of the rocker 1, a hub 4, forming its central portion and provided with a hole 6 for receiving a shaft (not shown) defining the pivot axis of the balance 1.
• the hub 4 is integrally connected to the serge 2 by arms 8.
• the arms 8 are here four in number and are arranged at 90 °. We find also usually balances with two or three arms, arranged respectively at 180 ° or 120 °.
• At least a portion of the rocker 1 is made of a partially or totally amorphous metal alloy. It will be understood by at least partially amorphous material that the material is able to be deformed plastically when it is heated to a temperature between its glass transition temperature and its crystallization temperature and capable of solidifying in the at least partially amorphous phase.
• said at least partially amorphous metal alloy is based on a member selected from the group consisting of platinum, zirconium and titanium, and has a coefficient of thermal expansion of between 7 ppm / ° C and 12 ppm / ° C.
• element-based means that said metal alloy contains at least 50% by weight of said element.
• Said at least partially amorphous metal alloy used in the present invention may be platinum-based and has a coefficient of thermal expansion of between 8 ppm / ° C and 12 ppm / ° C.
• Such an at least partially amorphous metal alloy based on platinum can consist, in values in atomic%, of
• the at least partially amorphous metal alloy used in the present invention can also be based on zirconium and has a coefficient of thermal expansion of between 8 ppm / ° C and 11 ppm / ° C.
• Such an at least partially amorphous metal alloy based on zirconium may consist, in values in atomic%, of
• the at least partially amorphous metal alloy used in the present invention can also be titanium-based and has a coefficient of thermal expansion of between 8 ppm / ° C and 11 ppm / ° C.
• Such an at least partially amorphous metal alloy based on titanium may consist, in values in atomic%, of
• the alloys used in the invention contain no impurities. However, they may include traces of impurities that can result, often unavoidably, the development of said alloys.
• platinum, titanium and zirconium alloys used in the present invention have the advantage of having a coefficient of thermal expansion of less than 12 ppm / ° C and greater than 7 ppm / ° C. They can therefore be used to achieve at least a portion of a pendulum which will be paired with a monocrystalline quartz spiral. More preferentially, said at least partially amorphous metal alloy used in the present invention based on platinum is constituted, in values in atomic%, of:
• Such an alloy has a coefficient of thermal expansion of between 11 and 12 ppm / ° C.
• said at least partially amorphous metal alloy used in the present invention based on zirconium is constituted, in values in atomic%, of:
• Such an alloy has a coefficient of thermal expansion of between 10.5 and 11 ppm / ° C.
• said at least partially amorphous metal alloy used in the present invention based on titanium is constituted, in values in atomic%, of:
• Such an alloy has a coefficient of thermal expansion of between 8 and 11 ppm / ° C.
• the serge 2, the hub 4 and the arms 8 are made of the same at least partially amorphous metal alloy based on platinum, zirconium or titanium as defined above.
• the rocker 1 is monobloc, that is to say, made in one piece.
• the rocker 1 may for example be made entirely of the platinum-based alloy as defined above. Platinum having a high density (21000 kg / m 3 ), the at least partially amorphous platinum-based alloy used in the invention also has a high density (15.5 g / cm 3 ), so the adding elements dense material to increase the inertia of the pendulum will not necessarily be necessary.
• the balance 1 can also be made entirely in the at least partially amorphous zirconium or titanium alloy as defined above.
• Zirconium or titanium having a lower density the at least partially amorphous zirconium or titanium-based alloy used in the invention also has a lower density (6.5 g / cm 3 for zirconium and 5.5 g / cm 3 for titanium), so that the addition of elements of denser material to increase the inertia of the balance is recommended, especially if one wishes to achieve a small balance for small movements. These elements make it possible to increase the inertia of the balance while keeping an aesthetic serge geometry and with good aerodynamic properties.
• the serge 2 may comprise overmolded first inertia adjusting elements 10, said first inertia adjusting elements being made of a material having a density greater than the density of said at least partially amorphous metal alloy.
• These first adjustment elements of the inertia 10 may for example be tungsten or tungsten carbide, and are obtained by overmolding.
• the serge 2 may comprise housings 12 intended to receive second elements for adjusting the inertia and / or unbalance 14, 15.
• These housings 12 may advantageously be provided during manufacture balance 1 by molding, as will be seen below.
• the second adjustment elements of the inertia and / or unbalance 14, 15 may be for example flyweights, slit weights, pins 14, cotter pins, or pins with unbalance 15, which act as flyweights. These elements are driven out or clipped into the corresponding housing 12.
• FIG. 3 are shown a pin 14 inserted in its housing 12, and a pin with unbalance 15 inserted into its housing 12.
• Figure 4 shows a sectional view along the line AA of Figure 3 showing the pin with unbalance 15 inserted into the housing 12 provided in the serge 2.
• the housings 12 shown in FIG. 3 may also constitute housings intended to receive decorative and / or luminescent elements, such as tritium tubes (not shown).
• the hub 4 may comprise integrated flexible centering elements, which allow a self-centering of the swing when it is mounted on an axis by virtue of the elastic deformation of said flexible centering elements.
• said integrated flexible centering elements 16 are elastic blades provided on the inner periphery of the hub 4 so as to be positioned in the hole 6.
• said integrated flexible centering elements 17 are provided on the 4 and the flexible centering elements 16 and 17 may advantageously be put in place during the manufacture of the balance 1 by molding, as will be seen hereinafter.
• At least one of the arms 8 carries third integrated flexible inertia adjustment elements.
• the end of the arm 8 on the side of the serge 2 ends in two branches 8a, 8b forming between them a housing 18 in which is integrated a third element of adjustment of the inertia 19 flexible bistable "V For setting the frequency.
• a third flexible buckling inertia adjustment element 20 is provided in the housing 18 for adjusting the frequency.
• the third adjustment element of the inertia 20 is made of a material having different expansion properties of the at least partially amorphous metal alloy based on platinum, zirconium or titanium of the balance of the invention. , such as silicon or silicon oxide.
• the end of the arm 8 on the side of the serge 2 terminates in three branches 8a, 8b, 8c forming between them two housings 18a, 18b in which third inertia adjustment elements 22a are integrated, 22b flexible multi-stable ratchet for frequency adjustment.
• These third flexible inertia adjusting elements 19, 20, 22a, 22b for the adjustment of the frequency can be used as well when the assembly of the balance is made of at least partially amorphous metal alloy based on zirconium, titanium or platinum according to the invention that when the arms are at least partially amorphous metal alloy based on zirconium, titanium or platinum according to the invention, the balance of the balance, and in particular the serge, being in another material.
• one of the arm 8, the serge 2 and the hub 4 has a structured surface state. Only one of the elements may have a structured surface condition or all the elements of the pendulum may have a structured surface state, this structured surface state may be the same or different.
• FIG. 10 represents a balance of the invention for which the serge 2 has a structured surface state different from the structured surface state presented by the arm 8. This structured surface state can be a polished, satin, sandblasted state, beaded, sunny, etc. It is also possible to provide in the mold for the manufacture of the balance microstructures forming a photonic network in order to replicate these microstructures on the surface of the balance.
• microstructures can make it possible to create a photonic crystal giving the piece a certain color, a hologram, or a diffraction grating that can constitute an anti-counterfeiting element.
• the structures are directly introduced into the mold, and are replicated during the manufacture of the balances by hot forming, which no longer requires termination operations.
• the arms and the hub of the balance are made in the at least partially amorphous metal alloy based on zirconium, titanium or platinum defined above, the serge being made in a material having a density greater than the density of said at least partially amorphous metal alloy used for the arms and the hub.
• This material may itself be the at least partially amorphous metal alloy based on platinum as defined above or another material.
• the arms and the hub of the balance are made of at least partially amorphous metal alloy based on zirconium or titanium as defined above to allow the pendulum to be paired with a monocrystalline quartz spiral
• the serge is made of another material having a density greater than the density of the at least partially amorphous metal alloy based on zirconium or titanium used for the arms and the hub in order to improve the inertia of the balance.
• the serge may comprise the same first inertial adjustment elements or the same housing for receiving the second adjustment elements of the inertia and / or unbalance or decorative and / or luminescent elements as described above for the first embodiment of the invention.
• the hub may comprise the same flexible centering elements integrated as those described above for the first embodiment of the invention.
• the arm may comprise the same integrated third flexible inertia adjusting elements as those described above for the first embodiment of the invention.
• the balance members may have structured surface states as described above for the first embodiment of the invention.
• the present invention also relates to a method of manufacturing a balance 1 for which the serge 2, the hub 4 and the arms 8 are made of said partially or totally amorphous metal alloy based on platinum, zirconium or titanium as defined above, comprising the steps of:
• step c) cooling said metal alloy at a chosen cooling rate to obtain a balance in said partially or totally amorphous metal alloy based on a member selected from the group consisting of platinum, zirconium and titanium d) release the balance obtained in step c) of its mold.
• the use of such a material also makes it possible to reproduce fine geometries very precisely because the viscosity of the alloy decreases sharply as a function of the temperature in the temperature range [Tg-Tx] and the alloy thus allies the details of the negative.
• the shaping is done around 300 ° C for a viscosity up to 10 3 Pa.s for a stress of 1 MPa, instead of a viscosity of 10 12 Pa.s at temperature Tg.
• the use of dies has the advantage of creating parts in three dimensions of high precision, which cutting or stamping do not achieve.
• One method used is the hot forming of an amorphous preform.
• This preform is obtained by melting the metal elements intended to form the partially or totally amorphous metal alloy based on platinum, zirconium or titanium in an oven. This fusion is made under a controlled atmosphere with the aim of obtaining as low a contamination of the oxygen alloy as possible. Once these elements melted, they are cast as a semi-finished product, then cooled rapidly to maintain the partially or totally amorphous state.
• the hot forming is performed in order to obtain a final piece. This hot forming is carried out by pressing in a temperature range between the glass transition temperature Tg and the crystallization temperature Tx of the metal alloy for a predetermined time to maintain an at least partially amorphous structure. This is done in order to maintain the characteristic elastic properties of the amorphous metals.
• the pressing time should not exceed about 120 seconds.
• hot forming makes it possible to maintain the at least partially initial amorphous state of the preform.
• the balance can be made by casting or injection.
• This process consists of casting or injecting the heated metal alloy at a temperature between its transition temperature vitreous and its crystallization temperature to be at least partially amorphous in a mold having the shape of the final piece. Once the mold is filled, it is rapidly cooled to a temperature below T g in order to avoid crystallization of the alloy and thus obtain an at least partially amorphous metal balance as defined above.
• the mold can be reused or dissolved to free the parts.
• the molding process has the advantage of perfectly replicating the geometry of the balance, including any decorations or surface patterning. Less dispersion of inertia and better centering on a rocker production batch are obtained.
• the molding process provides a balance with aesthetic geometry, with sharp interior angles, a serge profile and / or curved arm, and a perfect finish. It is also possible to provide a non-continuous serge.
• the mold will be made of silicon by a DRIE process. It is obvious that the mold can also be produced by machining by milling, laser, spark erosion or any other type of machining.
• the characteristic elastic properties of the at least partially amorphous metals are used to overmold or integrate functional and / or decorative elements in the serge and / or at the arms and / or at the hub for example by means of corresponding inserts placed in the mold before the introduction of the metal alloy heated between its glass transition temperature and its crystallization temperature to be at least partially amorphous.
• the method of the invention may comprise a step of overmoulding the first inertia adjusting elements 10 in the serge 2, by means of inserts placed in the mold before the introduction of the heated metal alloy between its glass transition temperature and its crystallization temperature to be at least partially amorphous and overmolded.
• the method of the invention may also comprise a step of overmolding the flexible centering elements 16, 17 on the hub 4, on its inner periphery or on its surface.
• the method of the invention may also comprise a step of overmoulding the third flexible inertia adjusting elements 19, 20, 22a, 22b in the arm 8.
• the molding method also makes it possible to provide a mold which has microstructures forming a decor or a photonic network so as to obtain the structured surface states on the arms and / or the hub and / or the serge as described above. It is also possible to add a logo to the mold.
• the present invention also relates to a method of manufacturing a rocker arm for which the hub and at least one arm are made of at least partially amorphous metal alloy based on zirconium, titanium or platinum defined above, the serge being made of a material having a density greater than the density of said at least partially amorphous metal alloy used for the arms and the hub, said method comprising the steps of: a) producing a mold having the negative shape of the balance a ') inserting into the mold a serge or serge elements made of a material having a density greater than the density of the at least partially amorphous metal alloy based on platinum, zirconium or titanium used for the arms and the hub b) introducing into the mold said at least partially amorphous metal alloy based on an element chosen from group consisting of platinum, zirconium and titanium, this metal alloy being heated to a temperature between its glass transition temperature and its crystallization temperature to be formed hot in the pendulum mold c) cooling said metal alloy at a selected cooling rate to obtain an
• step d) release the balance obtained in step c) of its mold.
• the present invention also relates to a resonator comprising a balance as defined above and a monocrystalline quartz spiral.
• the pendulum according to the invention is made of a material allowing to use a simple manufacturing process while having a coefficient of thermal expansion to match a spiral quartz monocrystalline.
• the balance according to the invention also makes it possible to have at least arms having a coefficient of thermal expansion making it possible to match it to a monocrystalline quartz spiral, while having great inertia while keeping a compact and aesthetic serge geometry, of small volume, using a suitable serge, either comprising elements made of a material of greater density, or being itself made of a material of greater density.

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• 2017
  • 2017-12-22 EP EP17210298.0A patent/EP3502786A1/de not_active Withdrawn
• 2018
  • 2018-12-03 CN CN201880081961.6A patent/CN111492318A/zh active Pending
  • 2018-12-03 US US16/767,778 patent/US11809137B2/en active Active
  • 2018-12-03 JP JP2020530619A patent/JP6982183B2/ja active Active
  • 2018-12-03 EP EP18808035.2A patent/EP3729201A1/de active Pending
  • 2018-12-03 WO PCT/EP2018/083295 patent/WO2019120959A1/fr unknown

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